Behavior of mercury in chemical looping with oxygen uncoupling of coal

Mercury pollution is a critical point in chemical looping with oxygen uncoupling combustion (CLOU) of coal. This work aims to investigate the behavior of mercury and the role of oxygen carrier (OC, CuO@TiO2-Al2O3) in the CLOU of Pingdingshan (PDS) anthracite. The average CO2 yield was 93.9% during the 15 redox cycles. The mercury balance was 119.0% ± 0.49 in the CLOU test (8 min, 4 repeated redox cycles). The distribution of Hg0(g) and Hg2+(g) was 0.033 ± 0.9*10−5 μg and 0.054 μg within the reduction process, respectively. The removal efficiency of Hg0(g) by the OC was 60.71%. Moreover, the Hg(p) was adsorbed on the OC with an adsorption capacity of 0.281 μg/g and was composed of 23.48% and 76.52% for Hg0 and Hg2+. The decreasing removal efficiency of Hg0 was listed as: OC + the complicated atmosphere of CLOU > OC + 5 vol% O2 > the completely oxidized OC > the partially reduced OC. The oxidation of Hg0(g) was promoted by sufficient active sites, absorbed oxygen and lattice oxygen of the OC. A long reduction time in the fuel reactor reduced the mercury released in the air reactor.